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4478P - Bernard 4478 Replacement O-Ring Kit (10-Pack)

Packaging: 10 per pak
$2.14/ea

Package Price:

$21.40/10 per pak

Usually ships within 3-5 business days

SKU: BER4478P Categories: ,

OVERVIEW

Technical Overview of the Bernard 4478P O-Ring Pack

The Bernard 4478P O-Ring (10 Pack) is a critical consumable component designed for the maintenance and repair of Bernard MIG welding guns. These O-rings are engineered to meet the specific dimensional and material requirements of Bernard Q-Gun, S-Gun, and T-Gun series systems. The primary function of the 4478 O-ring is to establish a hermetic seal within the gas delivery system of the MIG gun, typically located at the power pin connection or within the head assembly depending on the specific model configuration. By ensuring a tight seal, these components maintain the integrity of the shielding gas envelope, which is vital for meeting welding procedure specifications (WPS).

Manufactured from high-grade elastomer materials, these O-rings offer excellent resistance to compression set, ensuring they maintain their sealing properties even after repeated thermal cycling inherent in industrial welding operations. They are also formulated to resist degradation from exposure to ozone, lubricants, and anti-spatter compounds commonly found in welding environments. The 4478 part number is a standard replacement item, and this bulk packaging of 10 units allows for efficient inventory management in high-volume fabrication shops.

Failure to replace worn O-rings can lead to significant operational issues, including the aspiration of atmospheric air into the shielding gas stream (Venturi effect) or the direct loss of expensive shielding gas. This product addresses these mechanical failures directly. The 10-pack configuration is specifically targeted at maintenance departments and tool cribs, ensuring that technicians have immediate access to replacements during scheduled preventative maintenance (PM) or emergency repairs. Installation is straightforward and requires no specialized tooling, allowing for rapid turnaround and minimal machine downtime.

Key Technical Specifications:

  • Part Compatibility: Direct fit for Bernard 4478 specifications.
  • Material: Industrial-grade elastomer.
  • Function: Pneumatic sealing of shielding gas lines.
  • Packaging: Polybag containing 10 individual units.
Additional Information
Packaging Description:10 in a pack, 10 per pak
Item:O Ring
Brand:Bernard
Part Number:4478
Material:Elastomer
Compatibility:Bernard MIG Guns, Q-Gun Series, S-Gun Series
Application:Gas Sealing, Power Pin Seal

INCLUDED

  • 10 x 4478 Replacement O-Rings
  • Resealable packaging

APPLICATIONS

  • Sealing power pin connections on Bernard MIG guns
  • Preventing shielding gas leaks in industrial welding environments
  • Routine maintenance of Q-Gun and S-Gun assemblies
  • Repairing damaged or dried-out seals during liner changes
  • General fabrication and manufacturing equipment repair

FAQ

The 4478 O-ring is a standard part used in many Bernard MIG guns, including the Q-Gun, S-Gun, and T-Gun series. It is typically found on the power pin or within the head assembly to seal gas connections.

O-rings should be inspected whenever you perform maintenance, such as changing a liner. If they appear dry, cracked, or flattened, they should be replaced immediately to prevent gas leaks.

Common signs include audible hissing near the connection points, inconsistent gas flow at the nozzle, or porosity in the weld deposit despite having gas in the cylinder.

This product is a high-quality replacement part designed to meet or exceed the specifications of the original Bernard 4478 O-ring.

They are manufactured from a durable elastomer material designed to resist the heat, ozone, and chemicals typically found in welding environments.

Yes, absolutely. A damaged O-ring can allow air to be sucked into the gas stream (Venturi effect) or allow shielding gas to escape, both of which destroy the protective atmosphere around the weld pool.

This package contains 10 individual O-rings.

It is most commonly located on the power pin (the back end of the gun that plugs into the feeder) to create a gas-tight seal with the wire feeder.

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